The present invention relates to a method of controlling connections in a telecommunication system to which user terminals are connected. The telecommunication system comprises a control system for connection control, such as set up, release and modification of connections between user terminals. The control system comprises control resources as well as storage resources. The storage resources store control data related to said connections.
In particular the invention relates to a method of the indicated kind in a system that handles dynamic connections as well as semi-permanent connections.
U.S. Pat. No. 5,107,489 discloses a switch with an associated protocol for set up of dynamical connections by using frames. Each frame comprises an identifier identifying the source and the destination of the frame as well as link control information for maintenance, establishment and release of a connection between source and destination.
U.S. Pat. No. 5,115,425 discloses a distributed switch system comprising switch modules in a network. A call is handled in one of two modes. In a first mode unoccupied or free connections through the switch are selected quite regardless of if they are already established or not. In a second mode connections which are already established are selected.
U.S. Pat. No. 5,051,982 discloses a method and a system for fast set-up of circuit switched virtual connections in a digital circuit switched switch that integrates speech and data by using a common switch, a common control system and a common distribution system. Non-used bandwidth can be retrieved and dynamical connections can be so re-arranged that bandwidth utilization is optimized, thus providing for a maximum data speed at any time.
U.S. Pat. No. 4,821,256 relates to a method or monitoring information transmission in semi-permanent established 4-wire connections in digital time multiplex switches. Monitoring takes place by comparing bit streams and parity tests.
U.S. Pat. No. 5,046,183 relates to an arrangement so designed that when there is a call that should be debited the receiver or a third party, or when there is a personal call, an operator needs to be involved only after the call has been set up; the type of the call being displayed to the operator so as to assist the operator.
DE 38 18 087 relates to a telephone conference system comprising a permanent memory storing data relating to a number of participants which are to join a telephone conference. From one conference participant telephone conference connections can be set up to other conference participants.
A telecommunication system of the kind referred to above provides telecommunication services for which different types of connections between the user terminals can be controlled, such as for example be set up, be released and be modified.
For a first connection type said control is initiated from a user's terminal, for example a telephone or a computer. A user can initiate said control without involving an operator. The number of connections of this first type usually varies strongly over the time as does the respective durations of the connections; said durations often being short, for example some minutes or hours. Accordingly, connections of this type are very flexible. Such connections will in the following therefore be referred to as dynamical connections. An advantage of a dynamic connection is the swiftness by which it can be controlled and the simple way in which the control takes place.
For a second connection type said control is initiated by an operator of an operation and support terminal in an operation and support system. Connections of the second type usually are of a long duration, for example in the order of months. Compared with dynamical connections they are more static by nature. In the following, connections of the second type will be referred to as semi-permanent connections. An advantage of a semi-permanent connection is that it is less sensitive to disturbances, such as for example a non-desired release of the connection, than is a dynamic connection. This ability of not disturbing a connection is referred to as robustness.
The robustness of semi-permanent connections is better than that of dynamical connections and is provided by storing control data related to semi-permanent connections more reliably than control data related to dynamical connections. Said more reliable storage of control data is in the following referred to as persistent storage.
To control dynamical connections a first set of functions is used in the telecommunication system. To store semi-permanent connections a second set of functions is used. A majority of the functions of said second set are resident in a separate operation support system and are thus to a great extent separated from said first set of functions.
By using functions from said first set of functions, the control of dynamical connections can be initiated from a user's terminal, for example a telephone or a computer. Functions from said second set of functions are used to control connections of high robustness and said control is initiated from said operation support system. A problem associated with the control of semi-permanent connections from within an operation support system is that it takes a long time for a user until a robust connection is set up. This is so because the user must first inform the operator of the telecommunication system and then the operator must set up the connection. This is a process that takes a long time, perhaps several days.
The telecommunication system comprises several switching nodes interconnected in a network. The robustness of a dynamic connection that passes through several such switching nodes is low. In accordance with prior art technique the robustness of dynamical connections is increased for example by using more reliable hardware such as processors and switches which entails additional costs. The additional costs present a problem.
Dynamical connections make use of control resources such as processing capacity of a processor included in the control system, and volatile data storage resources such as RAM memories. The amount of control resources and data storage resources as used is proportional to the number of dynamical connections that have been set up. The supply of resources is scarce and will limit the number of dynamical connections that can be set up. This presents a problem.